<!doctype html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        span {
            color: white;
        }
        .content-center {
            display: flex;
            justify-content: center;
            align-items: center;
        }
        .header {
            background-color: #7dbcea;
            height: 3rem;
        }
        .content {
            background-color: #108ee9;
            flex: auto;
        }
        .footer {
            background-color: #7dbcea;
            height: 3rem;
        }
        .sider {
            background-color: #d7e6f1;
            width: 10rem;
            height: 30rem;
            display: flex;
            justify-content: center;
            align-items: center;
        }
        .content-body {
            display: flex;
            flex-direction: column;
            flex: auto;
        }
        .box {
            display: flex;
            flex-direction: row;
        }
    </style>
</head>
<body>
    <div class="box">
        <div class="sider content-center"><span>Sider</span></div>
        <div class="content-body">
            <div class="header content-center"><span>Header</span></div>
            <div class="content content-center"><span>Content</span></div>
            <div class="footer content-center"><span>Footer</span></div>
        </div>
    </div>
</body>
</html>